The Ruby Ranch in Southwestern Montana drive their cattle from their winter pastures to summer pastures in the Centennial Valley. Today, very few ranches drive their cattle with horses, instead moving them by truck. The age of the open range is gone and the era of large cattle drives over. Historically, cattle drives were a major economic activity in the American west, when millions of cattle were herded from Texas to railheads in Kansas for shipments to stockyards in Chicago and points east. The long distances covered, the need for periodic rests by riders and animals, and the establishment of railheads led to the development of "cow towns" across the American West.